1. Technical Field
The inventive arrangements relate generally to methods and apparatus providing advanced operating features for audio only, video only and both video and audio programs recorded on disc media, for example recordable digital video discs, hard drives and magneto optical discs.
2. Description of the Related Art
Various devices have been developed to enable consumers to record video and/or audio programs for later presentation. Such devices include tape recorders, video cassette recorders, recordable compact discs, and most recently, recordable digital video discs (DVD). Hard drives and magneto optical discs have also been used.
A DVD that can be recorded on only once, and thereafter is essentially a DVD read only memory, is referred to by the acronym DVD-R. The acronym DVD-R is also used generally to refer to the write-once, or record-once, technology. Several formats are available for DVD""s to be recorded on, erased and re-recorded; that is, overwritten or rewritten. These are referred to by the acronyms DVD-RAM, DVDxe2x88x92RW and DVD+RW. As of this time no uniform industry standard has been adopted. The acronyms DVD-RAM, DVDxe2x88x92RW and DVD+RW are also used generally to refer to the respective rewritable technologies. Reference herein to rewritable DVD technology, devices and methods is generally intended to encompass all of the standards which are now being used, as well as those which may be developed in the future.
Depending upon the standard that is eventually adopted, if any, certain recording schemes used to implement various advanced features will be compatible with all devices adhering to the standard, whereas other recording schemes may prove to be incompatible due to inconsistencies with the standard. Nevertheless, a particular proprietary advanced feature incompatible with other devices can still be very desirable from a consumer""s point of view. The result is merely that a recording made in accordance with an incompatible advanced feature cannot be played back on the device of a different manufacturer, even if conventional recordings are fully compatible and portable.
In many cases, the program presentations are recorded in the viewer and/or listener""s absence, for presentation at a later, more convenient time. This is referred to as time shifting the program. At other times, a program is being viewed and/or listened to without being recorded, and with out any interest in a recording, but the viewer""s and/or listener""s attention is interrupted, for example by a telephone call or an unexpected visitor. If the viewer and/or listener is watching a television program, for example, and has a cassette tape in a VCR, or can retrieve and load such a cassette tape quickly, the program can be recorded. However, the viewer and/or listener cannot view and/or listen to the program in its entirety, and in a proper time sequence, until after the recording has been completed. The time to completion of the recording can be short or long, depending on the length of the program.
Although rewritable DVD technology is generally available, operation is limited to such basic functions as play, record, fast forward reverse and stop. Pause is available, but only as a counterpart to pause operation in a VCR, for example interrupting the play back of a prerecorded program or interrupting the recording of a viewed program to eliminate commercials from the recording. Unlike computer hard drives, recordable DVD devices have a very significant additional function, which is playing back prerecorded DVD""s. Thus, there is an economic incentive to develop rewritable DVD technology, including methods and devices, that can be used instead of a computer hard drive. It is a challenge to provide such devices with improved, advantageous features without compromising the goal of decreasing costs and increasing sales.
DVD machines typically have a 1xc3x97 read and 1xc3x97 write capability. Such devices can typically have maximum data rates for recording or playing back of approximately 11 megabits/second. Thus, a key consideration for implementing certain copy functions for the purposes of the present invention is the relatively slow rate for reading and especially recording data on a DVD. This slow rate is attributable in large part to the nature of the mechanical assembly of conventional DVD devices and the limitations associated with reading and especially writing data to an optical disc.
For example, the high speed read access capability of conventional computer hard drives permit data to be read from discontinuous locations on the magnetic disc without any apparent interruption in the data. By comparison, with the relatively slower reading speed of a DVD, the data stream as physically located on the disc must be approximately continuous so as to avoid discontinuities in the playback of video or other media. Thus, a DVD copy feature requires data to physically be re-written to the proper location on the disc and cannot simply rely upon pointers or jump commands to physically separate areas of the disk.
It will be appreciated that in order to physically copy video data from one disk location to another as described above, a DVD device must have random access memory (RAM) for storing video data to be transferred. In fact, in order to accomplish this task efficiently, it is helpful to have as much RAM available as possible. However, inclusion of additional RAM in a DVD device adds expense which may not be acceptable to consumers. In fact, a key to the success of such DVD products is the ability of manufacturers to include new and useful features while continuing to reduce cost. Accordingly, a solution to the problem is required which allows the DVD copy feature to be implemented without the addition or expense of additional memory.
Rewritable DVD technology typically uses MPEG-2 encoders and decoders and many acronyms are encountered that are related to MPEG-2. The DVD standard, for example, calls for the video content of the disc to be divided up into video object units (VOBUs) in which each VOBU typically contains 0.4 to 1.0 seconds of presentation material. Each VOBU starts off with a navigation pack (NV_PCK or NAV_PACK). The navigation pack contains a lot of navigation information, some of which is very useful for trick modes. As used herein, trick modes refer to any operational mode for a recordable disc media other than the standard play mode. Thus, such modes can include reverse, fast forward, pause mode and so on.
The navigation pack includes presentation control information (PCI) and data search information (DSI). One example is the inclusion of the start addresses for many of the nearby VOBUs. This can facilitate jumping to the next VOBU forward or backward, or for a faster trick mode, to the second VOBU forward or backward, or to the third, etc. Another example is the inclusion of the end address for the first three reference pictures in the VOBU. This is the only clue given as to the structure of the VOBU.
Each video object set (VOBS) includes a plurality of video objects. Each video object includes a plurality of cells. Each cell includes a plurality of VOBUs. Each of the VOBUs containing the video content of the disc typically contains 0.4 to 1.0 seconds of presentation material. A typical VOBU in a commercial movie contains 0.5 second of presentation material, corresponding to one group of pictures (GOP). Each VOBU is a sequence of packs in recording order. Each VOBU starts with exactly one navigation pack and encompasses all of following kinds of packs, including a video pack (V_PCK), an audio pack (A_PCK) and a sub-picture pack (SP_PCK).
Data search information (DSI) helps the decoder to find reference pictures within the VOBU corresponding to the current Nav_Pack. DSI also helps the decoder to find VOBUs far into the future or past of presentation data, relative to the current VOBU. The VOBUs in the past relative to the current VOBU presentation are referenced in fields of the Nav_Pack known as the BWDI (backward information). The VOBUs in the future relative to the current VOBU presentation are referenced in fields of the Nav_Pack known as FWDI (forward information). One example is the inclusion of the start addresses for many of the nearby VOBUs, up to +240 VOBU forward and xe2x88x92240 VOBU backward directions. This can facilitate jumping to the next VOBU forward or backward, or for a faster trick mode, to the second VOBU forward or backward, or to the third, etc. The video, audio, subpicture, presentation control information and data search information are the five components of the DVD bit stream.
A method is provided for copying a recorded series of bits from a first location to a second location on a rewritable disc media. The method includes the steps of selectively marking a beginning point and an end point of a segment of the recorded series of bits, and a location to which said segment is to be copied prior to said reading step. Subsequently, video data comprising at least a portion of the segment of the recorded series of bits to be copied is read from the disk and stored in a track buffer of a DVD device. At least part of the video data from the track buffer is subsequently transferred directly from the track buffer to the record buffer by a control processor of the DVD device. Finally, the portion of the video data stored in the track buffer is written to the second location.
According to one aspect of the invention, the method can include the step of modifying one or more of a navigation pack, video pack, audio pack and subpicture pack data so that such information for the copied segment is correct as to the second location. Similarly, the method can include modifying a VTSI and the VMGI on the disc containing the second location.
According to yet another aspect, the method can include the step of comparing a video format of the segment to a video format of the bit stream at the second location. Such a comparison allows the control CPU or processor to determine if the video format of the source is the same as the destination.
In an alternative embodiment, a DVD device is provided for copying a recorded series of bits from a first location to a second location on a rewritable disc media. The device includes suitable DVD read and write circuitry, and special programming for implementing the copy function as described herein. The device includes interface circuitry and software for permitting a user to selectively mark a beginning point and an end point of a segment of the recorded series of bits, and a location to which the segment is to be copied. The device includes circuitry and programming for reading from the disk video data comprising at least a portion of the segment of the recorded series of bits, and for storing such data in a track buffer of the DVD device. A control processor and suitable interface circuitry is provided for causing at least part of the video data from the track buffer to be subsequently transferred directly from the track buffer to the record buffer. The device further includes suitable circuitry and programming for causing the portion of the video data stored in the track buffer to be written to the second location.
According to one aspect of the invention, the device can include the circuitry and software for modifying one or more of a navigation pack, video pack, audio pack and subpicture pack data so that such information for the copied segment is correct as to the second location. Similarly, the device can include circuitry and any necessary software for modifying a VTSI and the VMGI on the disc containing the second location.
According to yet another aspect, the device can include the circuitry and processing capability for comparing a video format of the segment to a video format of the bit stream at the second location. Such a comparison allows the control CPU or processor to determine if the video format of the source is the same as the destination.
Finally, if the content comprising the video segment is still useful, it can be temporarily stored in an available memory space until it is overwritten. Thus, this segment can remain in memory to be copied to another location, should the user so desire.